In many production and packaging systems where strip material is pulled off a supply roll either continuously or in closely succeeding steps, it is necessary to join the trailing end of the strip on the currently feeding roll to the leading end of a fresh roll so that there is no need to stop operations. Such on-the-fly roll switching frequently has to be done at high speed and has to be transparent, that is imperceptible in the downstream packaging or production operation.
As a rule, as described for instance in U.S. Pat. No. 6,500,288, published US patent application 2005/0239310, and WO 1998/002372, it is standard to mount the two supply rolls on respective parallel shafts immediately adjacent each other, and to provide a fast-acting splicer between them capable of joining the trailing end of the expiring roll to the leading end of the fresh roll. Once the changeover is completed, the empty core of the depleted roll is pulled off its shaft and is replaced with a fresh roll whose leading end is threaded to the splicer so it is ready for use.
Examples of applications can be found in the textile industry, printing machines and particularly also in the packaging industry, which all must meet high requirements in terms of purity and flawlessness when packaging pharmaceutical products. Furthermore, due to the finite length of the material strip provided on the supply roll, replacement of the supply roll on a regular basis is required, requiring automatic switchover from the active supply roil being used in the production process and the standby roll available as backup.